Engine noise simulator



July 25, 1961 G. s. ucHlHARA ENGINE NOISE sIMULAToR Filed Jan. 9, 1959 @gaga United States Patent O 2,994,078 ENGINE NOISE SIMULATOR George S. Uchihara, 1030 N. DearborrrSt., Chicago, Ill. Filed .Ian. 9, 1959, Ser. No. '785,935 9 Claims. (Cl. S40-384) This invention is concerned with a loud-speaker control circuit arrangement operating at a rate ydetermined by the excursion interval of an interrupter arm that is actuated by the diaphragm of the loud-speaker. This noisemaking assembly is remarkably simplified and economical in construction. More particular-ly, the invention is concerned with an arrangement that is capable of producing sound eiects realistically simulating the characteristic noise of a one-cylinder engine or putt-putt motor such as is commonly used for motor scooters. It is contemplated that the assembly of this invention may be attached to toy vehicles, and cost and realism `are hence of utmost importance.

It is the principal object of the present invention to provide `a simple battery-operated electric circuit arrangement that produces a realistic putt-putt sound characteristic of a single-cylinder engine.

Still a further object is to provide an arrangement that conveniently accommodates adjustment of the character and rate of the putt-putt sound.

Briefly the arrangement, according to this invention, depends upon the use of a resiliently swingable interrupter arm that is biased against the speaker cone or diaphragm to respond to a pulsing movement of the speaker cone and undergo substantially independent resilient swinging excursion movement.

The interval of this independent excursion movement of the interrupter arm substantially determines the puttputt rate of the sound produced by a loud-speaker. To accomplish this, the interrupter arm is arranged, upon movement from normal position, to open the electric circuit that supplies current for pulsing the diaphragm and as the arm returns to its normal position the circuit is closed and builds up another current pulse Ito again pulse the diaphragm and swing the arm through `an excursion movement during which the circuit is again open. Thus, the relatively slo-W swinging movement of the interrupter arm determines the .repetition rate of the pulses which actuate the speaker cone and, hence, determines the characteristic rate of the putt-putt sound produced by the speaker. According to the present invention, putt-putt rates as low as two or three per second are readily achieved, and rates in this range are required for developing a realistic engine noise.

`Other objects and advantages of the present invention Will become apparent as the description proceeds.

FIG. l is a side-sectional View through a speaker assembly that includes an interrupter arm in accordance with `this invention, and the electrical supply circuit for the speaker is shown diagrammatically; and

FIG. 2 is an enlarged fragmentary sectional view illustrating an alternative constructional arrangement of the interrupter arm.

IReferring now to the drawings and particularly to FIG. l thereof, the engine noise simulator embodiment of this disclosure is shown as including a loud-speaker 10 of conventional form that is connected in circuit with a source of steady D.C. voltage, with a current interrupter in the form of a resiliently swingable arm 11 causing the circuit to supply D.C. current pulses to the speaker -at a desired rate for producing a characteristic putt-putt sound. The interrupter arm normally reacts against the speaker cone or diaphragm 12 and responds to its highspeed excursion to undergo its own low-speed swinging -excursion movement, and with this arrangementthe excuri sion interval of the interrupter determines the D.C. pulse rate and, hence, the character of the sound produced.

For purposes of disclosure, the speaker is shown as comprising a generally conical frame 14 havin-g a permanent magnet 15 fixed adjacent the rear or apex of the frame to act in a direction axially thereof. The speaker cone or diaphragm 12 is anchored to the frame at its base end, with the apex of the cone adjacent the permanent magnet and provided with a mounting `form 12F for a voice coil 16. The polarity of the current through the voice coil determines the direction in which it is moved by the action of the permanent magnet. The speaker cone moves with the voice coil, and when the polarity of the voice coil current is such that the speaker cone kicks toward the interrupter arm 11, the interrupter arm is thereby pulsed into an independent swinging excursion movement during which it moves free of the speaker cone. A loud-speaker of this general type has been employed in the practice of this invention and is made by the Oxford Electrical Corporation, of Chicago, Illinois, under its Model Designation No. 4AMS, 4" P.M. 3.2 ohm voice coil, and power rating of 3-4 watts.

In the arrangement illustrated herein for purposes of disclosure, one lead of the voice coil is connected in circuit with a six-volt D.C. battery 17 and a twenty-ohm potentiometer 18 of a type preferably having an on-off switch and the other lead is connected through a circuitmaking contact arrangement that is under the control of the interrupter arm 11 and includes a contact plate 19, preferably of brass, that is adhesively secured to a felt pad 20 mounted across the apex of the cone, internally thereof, and a contact screw 21 and its mounting nut 21N that is carried on and resiliently swingable with the interrupter arm. The weight of the contact screw 21 and its nut 21N is correlated with the stiffness of the interrupter arm, it being heavy enough to develop suilicient momentum in response to actuation by the diaphragm to drive the interrupter arm through a substantial angular excursion. In this arrangement the interrupter arm itself is a current-carrying member, and it is shown in FIG. 1 as a spring-steel leaf or strip mounted in cantilever suspension from the base of the speaker frame 14 with a pair of insulating washers 22 and 23 spacing the mounting nut 24 and screw 25 and the interrupter arm itself from the speaker frame. When current is applied to the voice coil of the speaker, it drives the diaphragm of the speaker through a high-speed excursion to kick the interrupter arm 11 free of the contact plate 20 and break the actuating circuit for the diaphragm until the interrupter arm returns to normal position. The cycle repeats itself and the number of cycles per second, and hence the putt-putt rate is limited by the excursio-n interval of the relatively slow-moving resiliently swingable interrupter arm 11.

The noise-simulator unit is normally mounted with the face of the diaphragm arranged in a vertical plane; and thus, in normal use, the weight of the contact screw 21 and the nut 21N does not appreciably affect the neutral position of the interrupter arm 11. Since in use of this item, there will undoubtedly be situations where its normal vertical position cannot be maintained at all times, it is important that the arm have suiicient stiffness to resist the effects of gravity when the unit is inclined on the order of 5 from its normal position.

Thus'the characteristic resiliency and flexibility of the .swingable interrupter arm 11 are selected in accordance with the putt-putt rate which it is desired to achieve. The contact screw 21 is made yadjustable' to facilitate initial setting up of the apparatus and to allow a range of v adjustment of the putt-putt. sound. Similarly, the potenflcircuinthefaster is `the v`build-up time of-the current pulse 3 and, hence, `the faster is the putt-putt rate, though it will be appreciated that the characteristics of the interrupter arm tix the upper limit of the putt-putt rate.

When the current pulses in the voice coil are strong, there is a tendency for the resilient arm 11 to bounce to some extent, and this bouncing tendency can upset the uniformity of the pulse intervals. This can be substantially eliminated by means of a damper arm 27 that is fastened to the frame 14 of the speaker by a screw 28 and nut 29. The damper arm 27 is in the form of a substantially rigid strip of metal or other suitable material that is mounted to exert a slight pressure directly against the cone or diaphragm 12, and this prevents free vibration of the cone and minimizes the tendency for the interrupter arm 11 to bounce. There results a better regulated pulse interval and a more distinct and controllable putt-putt sound' at both low and high speeds.

The enlarged fragmentary view of FIG. 2 shows an alternative embodiment of the interrupter arm of this invention and in this instance, the arm 31 is rigid and is pivotally mounted on a bracket 32 with its free end carrying an adjustable contact screw 21 that is biased into engagement with a contact plate 19 mounted at the apex of the speaker cone. The biasing is provided by a coil spring 33 that reacts between a bracket 34 and a rearward extension 31K of the interrupter arm. The spring 33 is mounted in telescoping relation over the shank of a bolt 35 that extends through the rear extension 31k and a rear extension 34R of the bracket 34 to engage a suitable retaining nut 36. The brackets 32 and 34 may be of insulating material or the mounting fasteners shown generally at 37 for these brackets and the brackets themselves may be insulated from the frame 14 of the speaker. The bolt hole 34H in bracket 34 is enlarged to provide lateral clearance for accommodating swinging movement of the bolt 36 as it follows the interrupter arm 31. The action of the embodiment of FIG. 2 is similar to that of FIG. 1: each time the diaphragm 12 is pulsed towards the interrupter arm 31, the interrupter arm will undergo independent resilient swinging movement, during which separation of the contact screw 21 and the contact plate 19 opens the actuating circuit for the speaker diaphragm.

While the disclosed arrangements wherein the circuitmaking contacts are carried by the diaphrgam and interrupter arm are preferred, it will be apparent that one or both of the circuit-making contacts could be mounted from the frame of the speaker and' still be controlled by the excursion movement of the interrupter arm as it responds to the pulsing action of the diaphragm. Where the contacts are mounted from the frame, the interrupter arm need not be a current-carrying member. Such variations are contemplated within the broader scope of this invention.

The applicant is aware of the U.S. patents to Santino, 2,645,768, and McGonigle, 1,023,215. It is to be noted that the structures shown in these U.S. patents produce high-pitched beep-like sounds as determined by the excursion intervals of the speaker diaphragm, whereas the sound characteristics of the present device are in a much lower frequency realm, they being determined by the excursion interval of the interrupter member.

I claim:

y1. An engine noise simulator for producing a characteristic putt-putt" sound and comprising a frame, a diaphragm mounted on said frame for pulsing movement relative thereto, magnet means on said frame, a driving coil on said diaphragm to produce ux for reaction with said magnet means to generate pulsing movement of said diaphragm, means including an interrupter member mounted on said frame and having a normal position wherein it reacts against one side of the diaphragm and is responsive to pulsing movement of the diaphragm theretoward to undergo independent resilient swinging excursion' movement, said member having a swinging fre- ;quency on the order of a few cycles per second, and an electric circuit for pulsing said diaphragm and connected to said voice coil for supplying current of a polarity adapted to pulse said coil and diaphragm towards said member to initiate independent resilient swinging excursion movement said circuit including circuit-making contact means engageable by said member and held closed thereby only when said member is in its normal position such that the excursion interval of said member substantially determines the putt-putt rate.

2. In an engine noise simulator for producing a characteristic putt-putt sound, the combination with a speaker assembly that includes a frame, a diaphragm mounted on said frame, a permanent magnet mounted on said frame adjacent said diaphragm, and a voice coil mounted on said diaphragm adjacent said magnet and responsive to current ow therethrough to pulse said diaphragm; of means including an interrupter member mounted on said frame and having a normal position wherein it reacts against one side of the diaphrgam and is responsive to pulsing movement of the diaphragm theretoward to undergo independent resilient swinging excursion movement, said member having a swinging frequency on the order of a few cycles per second, and au electric circuit connected to supply current to said voice coil of a polarity adapted to pulse said diaphragm toward said member to initiate independent resilient swinging excursion movement, said circuit including circuit-making contact means engageable by said member and held closed thereby only when said member is in its normal position such that the excursion interval of said member substantially determines the putt-putt rate.

3. The arrangement of claim 2 wherein said contact means comprises a first contact mounted on said diaphragm on the side thereof adjacent said member and a second contact provided on said member and resiliently held against said first contact by said member to determine the normal position of said member, with the interrupting member being connected in current-carrying relation in said circuit.

4. ln an engine noise simulator, the combination with a frame, a permanent magnet secured to the frame, a speaker cone having a base anchored to the frame and having an apex adjacent the permanent magnet, a voice coil secured to the cone adjacent the cone apex and movable away from the permanent magnet upon passage of a current of predetermined polarity through the voice coil, and an electric supply circuit connected to the voice coil for energizing it with a current of said predetermined polarity; of means for interrupting said circuit at a low rate to produce a characteristic putt-put sound and comprising a contact mounted on and movable with `the speaker cone, and an interrupter member mounted on the frame and carrying a cooperating contact and having a swinging frequency on the order of a few cycles per second, said member having a normal position wherein it reacts against the diaphragm to hold the contacts closed, said member being responsive to pulsing movement of the diaphragm theretoward to undergo resilient swinging excursion movement during which it holds said contacts open, with the excursion interval of said member substantially determining the putt-putt rate.

5. The arrangement of claim 4 wherein said interrupter member is in the form of a strip of resiliently eXble material mounted as a cantilever suspension from the frame of said speaker, with the free end of the member resiliently reacting against the cone.

6. The arrangement of claim 4 wherein said interrupter member is in the yform of a rigid arm pivotally mounted from the frame to swing towards and away from the cone and spring means resiliently bias the interrupter member into reaction against the cone.

7. Apparatus for producing pulsating current at a low repetition rate and comprising a frame, a diaphragm mounted` on said frame for pulsing movement relative thereto, a permanent magnet mounted on said frame, a.

driving coil mounted on said diaphragm adjacent said magnet and responsive to current oW therethrough for moving said diaphragm in a direction determined by the polarity of the current, means including an interrupter member mounted on said frame and having a normal position wherein it reacts against one side of the diaphragm and is responsive to pulsing movement o f the diaphragm theretoward to undergo independent resilient swinging excursion movement at a frequency on the order of a few cycles per second, and an electric circuit having a constant voltage source of D.C. current connected to supply current to said coil of a polarity adapted to pulse said diaphragm toward said member, said circuit including circuit-making contact means engageable by said member and held closed thereby only when said mem* ber is in its normal position such that the apparatus produces pulsating current at a repetition rate substantially determined by the excursion interval of said member.

8. The arrangement of claim 7 wherein a relatively rigid damper arm is mounted on the frame to engage against said one side of the diaphragm and minimize free vibration of the diaphragm.

9. An engine noise simulator for producing a characteristic putt-pu sound and comprising a speaker assembly including a frame, a 'vibratile diaphragm mounted on said frame for pulsing movement relative thereto, a permanent magnet mounted on said frame adjacent said diaphragm and a driving coil mounted on said diaphragm adjacent said magnet and responsive to current iiow therethrough to pulse said diaphragm, an elongated interrupter member having a mounting point adjacent one end, mounting means for attaching the mounting point of the interrupter member to said frame to dispose the interrupter member in normal position wherein its other end reacts against one side of the diaphragm and is responsive to pulsing movement of the diaphragm theretoward to undergo independent resilient swinging excursion movement about said mounting point, said interrupter member having a frequency on the order of a few cycles per second and an electric circuit for pulsing said diaphragm, said circuit being connected to said driving coil to supply current of a polarity tending to pulse said diaphragm towards said interrupter member for initiating one cycle of independent resilient swinging excursion movement, said circuit including circuit-making contact means engageable by said interrupter member and held closed thereby only when said interrupter member is in its normal position such that the excursion interval of said member substantially determines the putt-put rate.

References Cited in the le of this patent UNITED STATES PATENTS 1,023,215 McGonigle Apr. 16, 1912 2,565,910 Conover Aug. 28, 1951 2,645,768 Santino July 14, 1953 FOREIGN PATENTS 740,743 France Nov. 21, 1932 

